A group of investigators at the Department of Biology of the University of Pennsylvania is requesting funds to purchase a JEM-1011 transmission electron microscope (TEM) equipped with an AMT- XR60 high resolution digital camera from JEOL USA Co. This equipment is needed to perform high resolution structural studies by laboratories of at least 10 faculty members in the Department, whose research is supported by 8 NIH and 3 NSF grants. Structural studies represent a critical component of biomedical research by allowing the direct visualization of the spatial organization of tissues, cells, organelles, and macromolecular complexes. Normally, availability of structural information radically drives a problem toward its solution. Electron microscopy is unique in its capability to provide structural information at high resolution level, because the resolution power of electron microscopy (0.2-0.4 nm) far exceeds that of light microscopy (a few hundreds of nm) explaining the need for electron microscopy in a broad range of research programs. Currently, a broad use of electron microscopy in the Department is significantly hampered by the lack of a reliable modern TEM. The requested TEM represents a basic model operating at the accelerating voltage of up to 100 kV, which is suitable for analysis of biological samples prepared by a variety of standard electron microscopic techniques. The requested microscope will replace the existing (currently non-functioning) ~ 40 years old Philips 200 TEM, which is the only TEM in the School of Arts and Sciences. There are five other TEMs in the Medical School, which are not available because they are fully used by the Departments to which they belong and/or because they have limited accessibility. Availability of a new microscope in the Department of Biology will help to establish a multi-user EM facility, which will greatly benefit research of multiple users supported by NIH grants and will attract others to use electron microscopy in the near future. Relevance: Electron microscopy is a unique tool to get insight into fine structural organization of tissues, cells, and molecules. Such structural information paves a road toward understanding of complex biological processes, without which it is not possible to fight a disease. [unreadable] [unreadable] [unreadable]